OCEAN CITY  Canadian snowbirds aren't the only northern tourists you might meet at the beach this summer.

An increasing number of young harp seals are straying from their northern breeding grounds and showing up on U.S. beaches, biologists say. Federal researchers say 297 harp seals were reported on beaches from Virginia to Maine last year, almost double the 152 reported in 1995.

The booming arctic harp seal population in Canada, spurred by a hunting ban, and dwindling food sources such as cod are among the reasons being cited.

"This is interesting and weird," said John Hocevar, a marine biologist with Greenpeace. "There has definitely been a healthy rebound in their numbers."

Greenpeace was among the groups that opposed hunting of baby harp seals, which are valued for their lush white fur. The seals that are showing up on Maryland beaches are usually about a year old and have already begun turning gray. Adult harp seals, named because of a harp-shaped marking on their backs, are gray with black faces, reaching maturity in four to six years, weighing about 300 pounds and measuring about six feet.

Six harp seals have been sighted on Maryland beaches over the past 18 months, according to the stranded marine mammal team at the National Aquarium in Baltimore.

Gordon Waring, a biologist in Woods Hole, Mass., with the National Oceanic and Atmospheric Administration, said the hunting ban has led to a population boom that is pushing the species farther south.

"The population is growing, with an estimated 5.5 million today," Waring told The (Baltimore) Sun.

While the population center is in Canadian waters, "it's not surprising, with the large number of harp seals, that some of them are now showing up in U.S. waters."

Commercial fishing of cod and other fish in the North Atlantic may have also driven the seals further south in search of food, said Jennifer Dittmar, a marine biologist with the National Aquarium.

Hocevar said harp seals still face an uncertain future, in part because of overfishing. In 2000, Canada allowed seal hunting again, permitting up to 400,000 young seals a year with gray coats to be taken.

Dittmar said the most recent stranding in the Chesapeake region was Feb. 8 when a sick harp seal was found in Bethany Beach, Del.

"It was observed eating sand," Dittmar said. "The seal had drainage from its eyes and nose and it was underweight."

The year-old female was taken to the National Aquarium in Baltimore, where it was given antibiotics to treat a mild case of pneumonia and fed herring and capelin. After gaining 25 pounds, the seal was released on April 6 near Ocean City.

Why seals like that one are showing up is not clear, but marine biologists say it's not for mating. Floating ice and much colder temperatures are needed for breeding.

The seals first venture off on their own at about a year old and have to swim more than a thousand miles to rejoin their colonies in Canada, Dittmar said.